Rejuvenation (aging)
Encyclopedia
Rejuvenation is the hypothetical reversal of the aging process
.
Rejuvenation is distinct from life extension
. Life extension strategies often study the causes of aging and try to oppose those causes in order to slow aging. Rejuvenation is the reversal of aging and thus requires a different strategy, namely repair of the damage that is associated with aging or replacement of damaged tissue with new tissue. Rejuvenation can be a means of life extension, but most life extension strategies do not involve rejuvenation.
or intervention of a supernatural
power can bring back the youth and many mythical adventurers set out on a journey to do that, for themselves, their relatives or some authority that sent them.
An ancient Chinese emperor actually sent out ships of young men and women to find a pearl that would rejuvenate him. This led to a myth among modern Chinese that Japan was founded by these people.
In some religions, people were to be rejuvenated after death prior to placing them in heaven
.
The stories continued well into the 16th century. A famous Spanish explorer Juan Ponce de León
led the expedition around the Caribbean islands and into Florida
to find the Fountain of Youth
. Led by the rumors, the expedition continued the search and many perished. The Fountain was nowhere to be found as locals were unaware of its exact location.
Since the emergence of philosophy
, sages
and self-proclaimed wizards always made enormous efforts to find the secret of youth, both for themselves and for their noble patron
s and sponsors. It was widely believed that some potion
s may restore the youth.
Another commonly cited approach was attempting to transfer the essence
of youth from young people to old. Some examples of this approach were sleeping with virgins or child
ren (sometimes literally sleeping, not necessarily having sex), bathing in or drinking their blood.
The quest for rejuvenation reached its height with alchemy
. All around Europe, and also beyond, alchemists were looking for the Philosopher's Stone
, the mythical substance that, as it was believed, could not only turn lead into gold, but also prolong life and restore youth. Although the set goal was not achieved, alchemy paved the way to the scientific method
and so to the medical advances of today.
Serge Abrahamovitch Voronoff was a French surgeon born in Russia who gained fame for his technique of grafting monkey testicle tissue on to the testicles of men while working in France in the 1920s and 1930s. This was one of the first medically accepted Rejuvenation Therapy (before he was proved to be wrong around 1930–1940). The technique brought him a great deal of money, although he was already independently wealthy. As his work fell out of favor, he went from being a highly respected surgeon to a subject of ridicule. By the early 1930s, over 500 men had been treated in France by his rejuvenation technique, and thousands more around the world, such as in a special clinic set up in Algiers
. Noteworthy people who had the surgery included Harold McCormick
, chairman of the board of International Harvester Company, and the aging premier of Turkey
.
In fiction, there is an increasing amount of work being done on possibilities of rejuvenation treatments, and the effect this would have on society. Misspent Youth
as well as the Commonwealth Saga
by Peter F. Hamilton
are one of the most well known examples of this, dealing with the short and long term effects of a near perfect 80-year-old to 20-year-old body change with mind intact. Also the Mars trilogy
deals with a much more imperfect type of rejuvenation, including problems such as long term memory loss and sheer boredom that comes with such age. Also the post mortal characters in the Revelation Space
series often illustrate this issue with long term or essentially infinite lifespans, sheer boredom induces them to undertake activities of extreme risk.
s, cells
, tissues
and organs
. If any of that damage can be repaired, the result is rejuvenation.
There have been many experiments which have been shown to increase the maximum life span
of laboratory
animals, thereby achieving life extension
. A few experimental methods such as replacing hormone
s to youthful levels have had considerable success in partially rejuvenating laboratory
animals and humans. A recent experiment involved breeding genetically manipulated mice that lacked an enzyme called telomerase, causing the mice to age prematurely and suffer ailments. When the mice were given injections to reactivate the enzyme, it repaired the damaged tissues and reversed the signs of aging. There are at least eight important hormones that decline with age: 1. human growth hormone (HGH); 2. the sexual hormones: testosterone or estrogen/progesterone; 3. erythropoietin
(EPO); 4. insulin; 5. DHEA; 6. melatonin; 7. thyroid; 8. pregnenolone. In theory, if all or some of these hormones are replaced, the body will respond to them as it did when it was younger, thus repairing and restoring many body functions.
Most attempts at genetic
repair have traditionally involved the use of a retrovirus
to insert a new gene
into a random position on a chromosome
. But by attaching zinc finger
s (which determine where transcription factor
s bind) to endonuclease
s (which break DNA
strands), homologous recombination
can be induced to correct and replace defective (or undesired) DNA sequences. The first applications of this technology are to isolate stem cell
s from the bone marrow
of patients having blood
disease mutation
s, to correct those mutations in laboratory dishes
using zinc finger endonucleases and to transplant the stem cells back into the patients.
Regenerative medicine
uses three different strategies:
A salamander
can not only regenerate a limb
, but can regenerate the lens
or retina
of an eye
and can regenerate an intestine
. For regeneration the salamander tissues form a blastema
by de-differentiation
of mesenchymal cells
, and the blastema
functions as a self-organizing system to regenerate the limb.
Yet another option involves cosmetic changes to the individual to create the appearance of youth. These are generally superficial and do little to make the person healthier or live longer, but the real improvement in a person's appearance may elevate their mood and have positive side effects normally correlated with happiness
. Cosmetic surgery is a large industry offering treatments such as removal of wrinkles ("face lift"), removal of extra fat (liposuction) and reshaping or augmentation of various body parts (abdomen
, breast
s, face
).
There are also, as always in history, many fake rejuvenation products that do not work. Chief among these are powders, sprays, gels, and homeopathic that claim to be "growth hormone". Authentic growth hormone can only be injected, because the 191 amino-acid protein is too large to be absorbed through the mucous membranes, and would break up in the stomach if it is swallowed.
. He calls his project to reverse the damage we call aging "SENS" (Strategies for Engineered Negligible Senescence). He has proposed seven strategies for what he calls the "seven deadly sins":
Dr. de Grey has created the Methuselah Mouse Prize, which awards money to researchers who can rejuvenate mice
.
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
.
Rejuvenation is distinct from life extension
Life extension
Life extension science, also known as anti-aging medicine, experimental gerontology, and biomedical gerontology, is the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan...
. Life extension strategies often study the causes of aging and try to oppose those causes in order to slow aging. Rejuvenation is the reversal of aging and thus requires a different strategy, namely repair of the damage that is associated with aging or replacement of damaged tissue with new tissue. Rejuvenation can be a means of life extension, but most life extension strategies do not involve rejuvenation.
Historical and cultural background
Various myths tell the stories about the quest for rejuvenation. It was believed that magicMagic (paranormal)
Magic is the claimed art of manipulating aspects of reality either by supernatural means or through knowledge of occult laws unknown to science. It is in contrast to science, in that science does not accept anything not subject to either direct or indirect observation, and subject to logical...
or intervention of a supernatural
Supernatural
The supernatural or is that which is not subject to the laws of nature, or more figuratively, that which is said to exist above and beyond nature...
power can bring back the youth and many mythical adventurers set out on a journey to do that, for themselves, their relatives or some authority that sent them.
An ancient Chinese emperor actually sent out ships of young men and women to find a pearl that would rejuvenate him. This led to a myth among modern Chinese that Japan was founded by these people.
In some religions, people were to be rejuvenated after death prior to placing them in heaven
Heaven
Heaven, the Heavens or Seven Heavens, is a common religious cosmological or metaphysical term for the physical or transcendent place from which heavenly beings originate, are enthroned or inhabit...
.
The stories continued well into the 16th century. A famous Spanish explorer Juan Ponce de León
Juan Ponce de León
Juan Ponce de León was a Spanish explorer. He became the first Governor of Puerto Rico by appointment of the Spanish crown. He led the first European expedition to Florida, which he named...
led the expedition around the Caribbean islands and into Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
to find the Fountain of Youth
Fountain of Youth
The Fountain of Youth is a legendary spring that reputedly restores the youth of anyone who drinks of its waters. Tales of such a fountain have been recounted across the world for thousands of years, appearing in writings by Herodotus, the Alexander romance, and the stories of Prester John...
. Led by the rumors, the expedition continued the search and many perished. The Fountain was nowhere to be found as locals were unaware of its exact location.
Since the emergence of philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
, sages
Wise old man
The wise old man is an archetype as described by Carl Jung, as well as a classic literary figure, and may be seen as a stock character...
and self-proclaimed wizards always made enormous efforts to find the secret of youth, both for themselves and for their noble patron
Patrón
Patrón is a luxury brand of tequila produced in Mexico and sold in hand-blown, individually numbered bottles.Made entirely from Blue Agave "piñas" , Patrón comes in five varieties: Silver, Añejo, Reposado, Gran Patrón Platinum and Gran Patrón Burdeos. Patrón also sells a tequila-coffee blend known...
s and sponsors. It was widely believed that some potion
Potion
A potion is a consumable medicine or poison.In mythology and literature, a potion is usually made by a magician, sorcerer, dragon, fairy or witch and has magical properties. It might be used to heal, bewitch or poison people...
s may restore the youth.
Another commonly cited approach was attempting to transfer the essence
Essence
In philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without...
of youth from young people to old. Some examples of this approach were sleeping with virgins or child
Child
Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...
ren (sometimes literally sleeping, not necessarily having sex), bathing in or drinking their blood.
The quest for rejuvenation reached its height with alchemy
Alchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
. All around Europe, and also beyond, alchemists were looking for the Philosopher's Stone
Philosopher's stone
The philosopher's stone is a legendary alchemical substance said to be capable of turning base metals into gold or silver. It was also sometimes believed to be an elixir of life, useful for rejuvenation and possibly for achieving immortality. For many centuries, it was the most sought-after goal...
, the mythical substance that, as it was believed, could not only turn lead into gold, but also prolong life and restore youth. Although the set goal was not achieved, alchemy paved the way to the scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of...
and so to the medical advances of today.
Serge Abrahamovitch Voronoff was a French surgeon born in Russia who gained fame for his technique of grafting monkey testicle tissue on to the testicles of men while working in France in the 1920s and 1930s. This was one of the first medically accepted Rejuvenation Therapy (before he was proved to be wrong around 1930–1940). The technique brought him a great deal of money, although he was already independently wealthy. As his work fell out of favor, he went from being a highly respected surgeon to a subject of ridicule. By the early 1930s, over 500 men had been treated in France by his rejuvenation technique, and thousands more around the world, such as in a special clinic set up in Algiers
Algiers
' is the capital and largest city of Algeria. According to the 1998 census, the population of the city proper was 1,519,570 and that of the urban agglomeration was 2,135,630. In 2009, the population was about 3,500,000...
. Noteworthy people who had the surgery included Harold McCormick
Harold Fowler McCormick
Harold Fowler McCormick, Sr. was chairman of the board of International Harvester Company.-Biography:He was born on May 2, 1872, the sixth child of Cyrus McCormick, inventor and manufacturer of the mechanical reaper; and Nancy Fowler McCormick.He graduated from Princeton University in 1895...
, chairman of the board of International Harvester Company, and the aging premier of Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
.
In fiction, there is an increasing amount of work being done on possibilities of rejuvenation treatments, and the effect this would have on society. Misspent Youth
Misspent Youth
Misspent Youth is a science-fiction novel by English author Peter F. Hamilton.Set in the near-future, it describes the story of Jeff Baker; an inventor who revolutionizes the world by creating the ultimate method of information storage and instead of selling it, offers it open source...
as well as the Commonwealth Saga
Commonwealth Saga
The Commonwealth Saga is a series of science fiction novels by British science fiction writer Peter F. Hamilton. This saga consists of the novels Pandora's Star and Judas Unchained , as well as Misspent Youth . The events of Pandora's Star and Judas Unchained take place 340 years after his...
by Peter F. Hamilton
Peter F. Hamilton
Peter F. Hamilton is a British author. He is best known for writing space opera. As of the publication of his tenth novel in 2004, his works had sold over two million copies worldwide.- Biography :...
are one of the most well known examples of this, dealing with the short and long term effects of a near perfect 80-year-old to 20-year-old body change with mind intact. Also the Mars trilogy
Mars trilogy
The Mars trilogy is a series of award-winning science fiction novels by Kim Stanley Robinson that chronicles the settlement and terraforming of the planet Mars through the intensely personal and detailed viewpoints of a wide variety of characters spanning almost two centuries...
deals with a much more imperfect type of rejuvenation, including problems such as long term memory loss and sheer boredom that comes with such age. Also the post mortal characters in the Revelation Space
Revelation Space
Revelation Space is a 2000 science fiction space opera novel by Welsh author Alastair Reynolds. It was the first novel set in the Revelation Space universe, although the then-unnamed universe had already been established by several published short stories....
series often illustrate this issue with long term or essentially infinite lifespans, sheer boredom induces them to undertake activities of extreme risk.
Ancient developments
The dream of longevity is a common heritage of humanity. The ancient researchers and practitioners of Siddha Vaidya in the east had developed strategies for the same reason, which believers in them feel were very effective. Followers of these therapies feel our current understanding of biology, physiology, immunology and biochemistry is helping us to decipher the rationale of these therapies. Ranging from detoxification of the body to targeted nutrition, believers feel these therapies can even produce invivo stimulation and deferentiation of stem cells into useful mature cells. Many of these longevity techniques are still practiced in South India. There is little evidence of their effectiveness.Modern developments
Aging is an accumulation of damage to macromoleculeMacromolecule
A macromolecule is a very large molecule commonly created by some form of polymerization. In biochemistry, the term is applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles...
s, cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
, tissues
Biological tissue
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
and organs
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
. If any of that damage can be repaired, the result is rejuvenation.
There have been many experiments which have been shown to increase the maximum life span
Maximum life span
Maximum life span is a measure of the maximum amount of time one or more members of a population has been observed to survive between birth and death.Most living species have at least one upper limit on the number of times cells can divide...
of laboratory
Laboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
animals, thereby achieving life extension
Life extension
Life extension science, also known as anti-aging medicine, experimental gerontology, and biomedical gerontology, is the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan...
. A few experimental methods such as replacing hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s to youthful levels have had considerable success in partially rejuvenating laboratory
Laboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
animals and humans. A recent experiment involved breeding genetically manipulated mice that lacked an enzyme called telomerase, causing the mice to age prematurely and suffer ailments. When the mice were given injections to reactivate the enzyme, it repaired the damaged tissues and reversed the signs of aging. There are at least eight important hormones that decline with age: 1. human growth hormone (HGH); 2. the sexual hormones: testosterone or estrogen/progesterone; 3. erythropoietin
Erythropoietin
Erythropoietin, or its alternatives erythropoetin or erthropoyetin or EPO, is a glycoprotein hormone that controls erythropoiesis, or red blood cell production...
(EPO); 4. insulin; 5. DHEA; 6. melatonin; 7. thyroid; 8. pregnenolone. In theory, if all or some of these hormones are replaced, the body will respond to them as it did when it was younger, thus repairing and restoring many body functions.
Most attempts at genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
repair have traditionally involved the use of a retrovirus
Retrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...
to insert a new gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
into a random position on a chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
. But by attaching zinc finger
Zinc finger
Zinc fingers are small protein structural motifs that can coordinate one or more zinc ions to help stabilize their folds. They can be classified into several different structural families and typically function as interaction modules that bind DNA, RNA, proteins, or small molecules...
s (which determine where transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
s bind) to endonuclease
Endonuclease
Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain, in contrast to exonucleases, which cleave phosphodiester bonds at the end of a polynucleotide chain. Typically, a restriction site will be a palindromic sequence four to six nucleotides long. Most...
s (which break DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
strands), homologous recombination
Homologous recombination
Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is most widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks...
can be induced to correct and replace defective (or undesired) DNA sequences. The first applications of this technology are to isolate stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
s from the bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
of patients having blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
disease mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s, to correct those mutations in laboratory dishes
Petri dish
A Petri dish is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch...
using zinc finger endonucleases and to transplant the stem cells back into the patients.
Regenerative medicine
Regenerative medicine
Regenerative medicine is the "process of replacing or regenerating human cells, tissues or organs to restore orestablish normal function". This field holds the promise of regenerating damaged tissues and organs in the body by replacing damaged tissue and/or by stimulating the body's own repair...
uses three different strategies:
- Implantation of stem cellStem cellThis article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
s from cultureCell cultureCell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...
into an existing tissueBiological tissueTissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
structure - Implantation of stem cells into a tissue scaffoldScaffoldingScaffolding is a temporary structure used to support people and material in the construction or repair of buildings and other large structures. It is usually a modular system of metal pipes or tubes, although it can be from other materials...
that guides restoration - Induction of residual cellsCell (biology)The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
of a tissue structure to regenerate the necessary bodyBodyWith regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...
part
A salamander
Salamander
Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant...
can not only regenerate a limb
Limb (anatomy)
A limb is a jointed, or prehensile , appendage of the human or other animal body....
, but can regenerate the lens
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
or retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
of an eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
and can regenerate an intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
. For regeneration the salamander tissues form a blastema
Blastema
A blastema is a mass of cells capable of growth and regeneration into organs or body parts. Historically blastema have been thought to be composed of undifferentiated pluripotent cells, but recent research indicates that in some organisms blastema may retain memory of tissue origin...
by de-differentiation
Cellular differentiation
In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a simple zygote to a complex system of...
of mesenchymal cells
Mesenchymal stem cell
Mesenchymal stem cells, or MSCs, are multipotent stem cells that can differentiate into a variety of cell types, including: osteoblasts , chondrocytes and adipocytes...
, and the blastema
Blastema
A blastema is a mass of cells capable of growth and regeneration into organs or body parts. Historically blastema have been thought to be composed of undifferentiated pluripotent cells, but recent research indicates that in some organisms blastema may retain memory of tissue origin...
functions as a self-organizing system to regenerate the limb.
Yet another option involves cosmetic changes to the individual to create the appearance of youth. These are generally superficial and do little to make the person healthier or live longer, but the real improvement in a person's appearance may elevate their mood and have positive side effects normally correlated with happiness
Happiness
Happiness is a mental state of well-being characterized by positive emotions ranging from contentment to intense joy. A variety of biological, psychological, religious, and philosophical approaches have striven to define happiness and identify its sources....
. Cosmetic surgery is a large industry offering treatments such as removal of wrinkles ("face lift"), removal of extra fat (liposuction) and reshaping or augmentation of various body parts (abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
, breast
Breast
The breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.Both men and women develop breasts from the same embryological tissues...
s, face
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
).
There are also, as always in history, many fake rejuvenation products that do not work. Chief among these are powders, sprays, gels, and homeopathic that claim to be "growth hormone". Authentic growth hormone can only be injected, because the 191 amino-acid protein is too large to be absorbed through the mucous membranes, and would break up in the stomach if it is swallowed.
Strategies for Engineered Negligible Senescence (SENS)
The leading modern exponent of scientific rejuvenation is the biomedical gerontologist Dr. Aubrey de GreyAubrey de Grey
Aubrey David Nicholas Jasper de Grey is an English author and theoretician in the field of gerontology, and the Chief Science Officer of the SENS Foundation. He is editor-in-chief of the academic journal Rejuvenation Research, author of The Mitochondrial Free Radical Theory of Aging and co-author...
. He calls his project to reverse the damage we call aging "SENS" (Strategies for Engineered Negligible Senescence). He has proposed seven strategies for what he calls the "seven deadly sins":
- Cell loss can be repaired (reversed) just by suitable exercise in the case of muscleMuscleMuscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
. For other tissues it needs various growth factorGrowth factorA growth factor is a naturally occurring substance capable of stimulating cellular growth, proliferation and cellular differentiation. Usually it is a protein or a steroid hormone. Growth factors are important for regulating a variety of cellular processes....
s to stimulate cell divisionCell divisionCell division is the process by which a parent cell divides into two or more daughter cells . Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort...
, or in some cases it needs stem cells. - Senescent cellsCell (biology)The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
can be removed by activating the immune systemImmune systemAn immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
against them. Or they can be destroyed by gene therapyGene therapyGene therapy is the insertion, alteration, or removal of genes within an individual's cells and biological tissues to treat disease. It is a technique for correcting defective genes that are responsible for disease development...
to introduce "suicide geneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s" that only kill senescent cells. - ProteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
cross-linking can largely be reversed by drugsMedicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
that break the links. But to break some of the cross-links we may need to develop enzymatic methods. - ExtracellularExtracellularIn cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...
garbage (like amyloidAmyloidAmyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various neurodegenerative diseases.-Definition:...
) can be eliminated by vaccinationVaccinationVaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
that gets immune cells to "eat" the garbage. - For intracellular junk we need to introduce new enzymeEnzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s, possibly enzymes from soil bacteriaBacteriaBacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, that can degrade the junk (lipofuscinLipofuscinLipofuscin is the name given to finely granular yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, adrenals, nerve cells, and ganglion cells...
) that our own natural enzymes cannot degrade. - For mitochondrial mutations the plan is not to repair them but to prevent harm from the mutations by putting suitably modified copies of the mitochondrial genes into the cell nucleusCell nucleusIn cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
by gene therapy. The mitochondrial DNAMitochondrial DNAMitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
experiences a high degree of mutagenic damage because most free radicalsRadical (chemistry)Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
are generated in the mitochondria. A copy of the mitochondrial DNA located in the nucleusCell nucleusIn cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
will be better protected from free radicals, and there will be better DNA repairDNA repairDNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and radiation can cause DNA damage, resulting in as many as 1...
when damage occurs. All mitochondrial proteinProteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s would then be imported into the mitochondria. - For cancerCancerCancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
(the most lethal consequence of mutations) the strategy is to use gene therapyGene therapyGene therapy is the insertion, alteration, or removal of genes within an individual's cells and biological tissues to treat disease. It is a technique for correcting defective genes that are responsible for disease development...
to delete the geneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s for telomeraseTelomeraseTelomerase is an enzyme that adds DNA sequence repeats to the 3' end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. This region of repeated nucleotide called telomeres contains non-coding DNA material and prevents constant loss of important DNA from...
and to eliminate telomerase-independent mechanisms of turning normal cells into "immortal" cancer cells. To compensate for the loss of telomerase in stem cells we would introduce new stem cells every decade or so.
Dr. de Grey has created the Methuselah Mouse Prize, which awards money to researchers who can rejuvenate mice
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
.
Scientific journal
- Rejuvenation ResearchRejuvenation ResearchRejuvenation Research is a multidisciplinary peer-reviewed bimonthly scientific journal published by Mary Ann Liebert that investigates rejuvenation therapies.The editor-in-chief is Aubrey de Grey...
Editor: Aubrey de GreyAubrey de GreyAubrey David Nicholas Jasper de Grey is an English author and theoretician in the field of gerontology, and the Chief Science Officer of the SENS Foundation. He is editor-in-chief of the academic journal Rejuvenation Research, author of The Mitochondrial Free Radical Theory of Aging and co-author...
. Publisher: Mary Ann Liebert, Inc.Mary Ann Liebert, Inc.Mary Ann Liebert, Inc. is a publishing company founded by its current president, Mary Ann Liebert, in 1980. The company publishes peer-reviewed academic journals, books, and trade magazines in the areas of biotechnology, biomedical research/life sciences, clinical medicine, alternative/integrative...
ISSN 1549-1684 – Published Quarterly.
Further reading
- Gavrilov L.A., Gavrilova N.S. 2010. Demographic Consequences of Defeating Aging. Rejuvenation Research, 13(2-3): 329-334.
External links
- SENS Foundation
- Regenerative Medicine and Rejuvenation
- Life Extension magazine interview about rejuvenation science
- Resources and Articles on the Biology of Aging and Life-Extension
- The Biogerontology Research Foundation - a UK-based charity focused on rejuvenation research
- Aging Cell - an online publication covering the novel rejuvenation mechanisms